OSPF and VLANs

[Happymofugu]

Good morning everyone,

I have some questions regarding Meraki L3 switches.

Long story short, I need some guidance since this has been one difficult route.

I have MS250 L3 switches that all need to talk together.

4 of the switches are in the core and they're stacked together running OSPF 0 for the area.

All the other locations are trunked back to the stacked switches via SMF fiber.

For those branch locations, should the OSPF be a different area or can they all be apart of the same area?

Also, when it comes to VLANs, lets say VLAN 50 is on one of the branch switches with an interface of 10.0.50.1. Does the spot they go back to need to also have a VLAN interface in order to work properly and if so, why? We have one interface which is a management interface which isn't relayed but the other VLANs that are specifically for there location are being relayed back to the stack where they receive DHCP. 

Also, with OSPF at the branch locations. Do I need to configure static routes or can this be disregarded and just allow OSPF to do it all?

[alemabrahao]

Areas

Area types in OSPF are used to define what kinds of Link State Advertisements (LSAs) will be found within an area, and determine how the route table will be generated in each area.

MS switches support 3 area types:

• Normal Areas
• Stub Areas
• Not-So-Stubby Areas (NSSA). 

Each area in Dashboard requires an Area ID, a descriptive name, and the type of area. If configuring an MS to be part of an existing OSPF Autonomous System and/or Area.

Full doc: https://documentation.meraki.com/MS/Layer_3_Switching/MS_OSPF_Overview

I recommend splitting It by area.

[Happymofugu]

This is interesting.

What about the VLAN situation?

[alemabrahao]

The VLANs on the same site use the same area. Something like that:

[Happymofugu]

I see, so the VLANs won't be on the other switches besides the one they're supposed to be on.

So with that being said, let's say we have the following below.

OSPF Area 1:

Interface: VLAN 50 - 10.0.50.1 (Management) Not Relayed

Interface: VLAN 60 - 10.0.60.1 (Relayed 10.0.10.71)

Interface: VLAN 70 -10.0.70.1 (Relayed 10.0.10.71)

OSPF Area 0:

Interface VLAN 10 - 10.0.10.1

Area 1 is trunked to Area 0:

Trunk port: 50,60,70

The DHCP server is running on VLAN 10 on the backbone.

What would I set the static route to be for Area 1 back to Area 0?

[alemabrahao]

Yes, you can create a static route and advertise it on OSPF:

I have never tried It, but It should work.

https://documentation.meraki.com/MS/Layer_3_Switching/MS_OSPF_Overview#Static_Routes